Insect infestation reduction method

ABSTRACT

A method of preventing infestation of a bed by creeping insects; said method including the application of a barrier to the legs of said bed; said barrier comprising a disc or layer of material inimical to at least a selection of said creeping insects; said disc or layer interposed between an upper end of each bed leg and the underside surface of a bed base of said bed.

The present invention relates to pest control and, more particularly, tobed bug and other creeping insect infestation minimisation technology.

BACKGROUND

One example of an insect likely to infest is the common bed bug, (Cimexlectularius), a small insect, adults growing to 4-5 mm, found throughoutthe temperate world. It feeds on blood and is well adapted tocohabitation with humans, particularly preferring to infest bedding.

Infestation is a particular problem in those facilities catering torevolving clientele, such as hotels, guest houses, backpacker hostelsand other forms of guest accommodation, but can also become a seriousproblem in the home.

Infestation of a bed may occur in at least two ways. Firstly, bugs maybe introduced into the bed from luggage, contaminated clothing or evenfrom human carriers. Secondly, bugs may initially be present in carpetsor rugs and thence find their way into the bed by crawling up the bedsupporting structure.

Although infestation by bed bugs is perhaps the most common problem, itis clearly undesirable to have one's bed invaded by any creepinginsects.

Various attempts have been made to solve problems found in pest controlart. Among these are found in: U.S. Patent and Publication Nos.2013/0067796 to Dong et al., 2013/0042520 to Snell, 2013/0111801 toWhite et al., 2011/0225873 to McKnight et al., D668,314 to MacKay etal., and 2012/0096759 to Biggs. This prior art is representative of pestcontrol means.

None of the above inventions and patents, taken either singly or incombination, is seen to describe the invention as claimed. Thus, a needexists for a reliable insect infestation reduction system, and to avoidthe above-mentioned problems.

It is an object of the present invention to address or at leastameliorate the problem of insect infestation routes.

NOTES

-   1. The term “comprising” (and grammatical variations thereof) is    used in this specification in the inclusive sense of “having” or    “including”, and not in the exclusive sense of “consisting only of”.-   2. The above discussion of the prior art in the Background of the    invention, is not an admission that any information discussed    therein is citable prior a or part of the common general knowledge    of persons skilled in the art in any country.

BRIEF DESCRIPTION OF INVENTION

Accordingly, in one broad from of the invention there is provided amethod of preventing infestation of a bed or other item of furniture bycreeping insects; said method including the application of a barrier atthe legs of said bed or furniture; said barrier comprising at least onedisc or layer of material inimical to at least a selection of saidcreeping insects; said disc or layer interposed between a ground surfaceand the underside surface of a bed base of said bed or between a groundsurface and an upper structure of said furniture.

Preferably at least one said disc or layer has a low coefficient offriction surface; said surface having properties preventing a creepinginsect traversing a substantially horizontal underside of said disc orlayer.

Preferably said properties include a low coefficient of friction andresistance to van der Waal forces.

Preferably said low coefficient of friction of said surface is a dynamiccoefficient of friction less than 0.4.

Preferably said disc layer is composed of polytetrafluoroethylene orsimilar compounds; such compounds commonly known as Teflon®.

Preferably said disc or layer is sized so as to extend beyond theperiphery of said bed leg; an extended portion of said disc or layerforming a substantially horizontal annular underside surface beyond saidperiphery.

Preferably said disc or layer is provided with a central aperture; saidaperture sized so as to allow passage therethrough of a securing bolt ofsaid bed leg.

Preferably said disc comprises a dual ring assembly; the assemblyincluding an outer ring and an inner ring affixed to said outer ring;the outer ring formed of a substantially rigid polymer with said lowcoefficient of friction; the inner ring formed of a flexible polymer;each said outer ring and said inner ring provided with a centralaperture.

Preferably flexibility of said inner ring, provides for said dual ringassembly to be retained on a leg of a bed or other item of furniturepassing through said aperture in said inner ring; said dual ringassembly retained on said leg by friction between said leg and saidflexible inner ring.

In yet a further broad form of the invention there is provided a methodof reducing infestation of a bed by climbing insects; said methodincluding interposing insect impeding barriers at supporting elements ofsaid bed; said method including the steps of

-   -   (a) detaching each supporting element of said bed;    -   (b) applying said insect impeding barrier to an upper end of        said supporting element;    -   (c) re-attaching said supporting elements to said bed such that        said barrier is interposed between said upper end of said        supporting element and an underside of said bed.

Preferably said supporting element is a bed leg; said bed leg attachingto an underside of a bed base of said bed by a length of threaded rodprojecting from said upper end of said bed leg; said barrier formed as adisc or layer of low friction material; said disc or layer sized toproject radially from a periphery of said bed leg so as to expose anannular surface of said low friction material forming a substantiallyhorizontal underside surface between a periphery of said bed leg andsaid underside of said bed.

Preferably said method includes the further steps of interposing offsetblocks between a bed head of said bed and an adjacent wall; said offsetblocks including an insect impeding barrier.

Preferably said insect impeding barrier includes application of a lowcoefficient of friction tape to surfaces of said offset blocks; saidoffset blocks configured so as to present one or more upwardly slopingupper surface only, between said bed head and said adjacent wall.

Preferably said insect impeding barrier includes a ring of lowcoefficient of friction material; said ring of material includingvertical surfaces projecting radially from surfaces of said offsetblocks.

In yet a further broad form of the invention there is provided a methodof preventing infestation by creeping insects of a bed or other elevatedstructure; said method including the application of a barrier in theform of a gasket or washer to the legs or substructure of said bed orother elevated structure; said barrier comprising a band of a materialinimical to at least a selected group of said creeping insects.

Preferably said band of material is treated, with a compound; saidcompound having properties repulsive to at least a group of saidcreeping insects.

Preferably said gasket or washer is formed of a porous material; saidcompound impregnated into said porous material.

In yet a further broad form of the invention there is provided a disc ofmaterial forming a barrier extending generally radially from a peripheryof a bed leg between a floor surface and a bed base; said disc ofmaterial inimical to traversing by bed bugs and other creeping insects;said disc comprising a dual ring assembly of an outer ring and an innerring affixed to said outer ring; said outer ring presenting an exposedsubstantially horizontal underside, annular portion, of low coefficientof friction material.

Preferably said disc is provided with a central aperture for placementof said discover a central securing bolt of a said bed leg or aroundsaid bed leg.

In yet a further broad form of the invention there is provided a kit forproviding protection of infestation of a bed by bed bugs and otherclimbing insets; said kit comprising packaging containing a number ofdiscs or layers of a low coefficient of friction material; said discs orlayers adapted for interposing between upper portions of bed legs andthe underside of a bed base of said bed.

BRIEF DESCRIPTION OF DRAWINGS

Embodiments of the present invention will now be described withreference to the accompanying drawings wherein:

FIG. 1 is a side view of typical support structure of a bed base,

FIG. 2 is a side view of the support structure of FIG. 1 to which apreferred arrangement of the bed bug reduction method of the inventionhas been applied,

FIG. 3 is a side view of a support structure with castor when fittedwith a castor and provided with the arrangement of the bed bug reductionmethod of FIG. 2,

FIG. 4 is a side view of a portion of another typical support structureof a bed provided with the bed bug reduction method of the invention,

FIG. 5 is a side view of the framing of a bunk bed provided with the bedbug reduction method of the invention.

FIG. 6 is a side view of the method of installation according to afurther embodiment of the present invention.

FIG. 7 is a side view of the bed after installation according to themethod illustrated in FIG. 6,

FIG. 8 is a perspective view of an experimental installation showing afurther embodiment under test conditions,

FIG. 9 shows tables summarizing results of the experiments of FIG. 8,

FIG. 10 shows a further embodiment of a bed bug reduction methodaccording to the invention installed between a bed head and adjacentwall,

FIG. 11 shows a further embodiment of a bed bug barrier installedbetween a bed head and adjacent wall

FIGS. 12 to 15 are cross section views of a still further embodiment ofa bed bug or other creeping insect reduction method according to theinvention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS First Preferred Embodiment

The present invention seeks to reduce the incidence of bed bug and othercreeping insect infestation of beds by substantially eliminating oneroute by which creeping insects can gain access to a bed, or otherelevated structure from a supporting ground surface.

With reference to FIGS. 1 and 2, bed bases 10 and other structures arefrequently supported by four or more legs 12 resting directly on thefloor 14 or the legs may be mounted on castors 16 as shown in FIG. 3.Typically, legs are manufactured of some suitable material such a wood,which although apparently smooth, provide ample purchase to bed bugs,which are excellent climbers, as are most other creeping insects, Nor docastors, typically formed of plastic or metal and plastic assemblies,provide any barrier to a bed bug or other creeping insect.

The present invention resides in the provision of a barrier locatedalong the substantially vertical surfaces of supporting structures ofbed bases and other elevated structures.

It has been found, that some materials with sufficiently low coefficientof friction and resistance to van der Waal forces, when forming asubstantially vertical surface, provide an effective barrier to climbinginsects, Such materials include polytetrafluoroethylene or similar PTFEcompounds such as that commonly known as Teflon® by the Americanchemical manufacturer Dupont. Depending on the particular grade andcompound this material has a coefficient of friction of around 0.4.

In this first preferred embodiment, the present invention provides amethod of creeping insect infestation reduction by the application of alow coefficient of friction, material to the substantially verticalsurfaces of the support structures of beds. Preferably, the dynamiccoefficient of friction of the material is less than 0.4. The methoddescribed in this specification refers to the use of Teflon® but it willbe understood that any material, with a coefficient of frictionsufficiently low so as to deny purchase to a climbing creeping insects,is envisaged in the invention.

Referring again to FIGS. 2 and 3, it can be seen that at least a portionof the leg 12 has been provided with an annular coating 18 of Teflon®extending a sufficient distance up the leg to provide a barrier. Theextent of the coating is preferably at least 10 mm, but more preferablyis not less than 25 mm.

A Teflon® coating may be applied as a liquid to the material from whicha bed leg is made. Alternately it may be applied as a film of material,or in another arrangement, at least a portion of the leg could bemanufactured from Teflon® itself, for example in the form of “feet”affixed at the lower end of the leg.

FIG. 4 shows another support structure for a bed base, in this case aperimeter frame 20 resting directly on the floor. In this situation, aband 22 of Teflon® material may be applied right around the frame todeny access to creeping insects.

FIG. 5 shows a portion of a bunk bed, the framing 24 of which typicallyis also in direct contact with the floor. In this instance theprevention method of the invention is similar to that applied to the legshown in FIG. 2, that is by applying a band 28 of Teflon® to at least aportion of each of the vertical frame members 26 of the bunk bed.Alternatively, as described above, Teflon® “feet” could be fitted at thebase of each of the vertical frame members.

Second Preferred Embodiment

With reference to FIGS. 6 and 7 there is illustrated a furthermethodology in accordance with a further preferred embodiment of thepresent invention. Like components are numbered as for the firstembodiment above.

In this instance, the methodology for interrupting the route by whichcreeping insects can gain access to a bed or other elevated structure bymeans of its supporting legs or substructure, is by way of interposing abarrier, in this instance, in the form of a gasket 20 or washer 21.

In the preferred methodology the gasket or washer is made from Teflon,or similar low coefficient of friction material, and is preferablyinterposed along the route as a barrier. The steps of installation ofthe barrier, for example in the case of a bed supported on legs, includeunscrewing the leg 12, placing the gasket or washer 20, 21 on the uppersurface 22 of leg 12 around a length of threaded rod 23 projecting fromthe leg, reinstalling the leg 21 by screwing threaded rod 23 into athreaded recess 24, thereby to arrive by at the arrangement shown inFIG. 7. By this arrangement the washer or gasket 20, 21 provides abarrier entirely across the route which a creeping insect might takefrom surface 14 via exterior of leg 12 to the mattress 25.

By this arrangement, broadly speaking, there is disclosed the use of abarrier treated with (or made entirely from) Teflon® or similar materialinterposed between the floor and bed for the purposes of preventing orat least minimising the possibility of creeping insects from climbingfrom the floor to the bed or bedding. The barrier may take the form ofthe washer/disc or gasket as described above or it may take any otherform of barrier. In the preferred form the barrier is arranged, as muchas possible, to appear as part of the leg assembly so that it is notvisually displeasing.

Although a very low coefficient material clearly has maximum effect ifapplied to a vertical surface, for some insects at least, a materialsuch as Teflon, may also provide a significant impediment to at leastsome creeping insects when applied to a sloping or even an horizontalsurface.

Third Preferred Embodiment

It will also be readily understood that a low friction surface mayprovide an even greater impediment to a crawling insect if that surfacehas significant negative slope, with the maximum effect achieved if thesurface is a substantially horizontal underside. Thus in one preferredform of the gasket or washer shown in FIG. 7, the washer extends beyondthe section of the leg to which it is applied as shown in FIG. 7A, thuscreating an exposed annular, substantially horizontal, underside surface26 as well as a further substantially vertical surface.

In a particularly preferred arrangement shown in FIG. 8, the barrierfitted to a leg of a bed, may be comprised of a relatively thin disc orlayer 20 of low friction material with a diameter, or in extent,significantly larger than the diameter or area of the upper end of leg12. As previously described, the disc or layer 20 is provided with acentral aperture of sufficient diameter to allow passage of the legsecuring bolt, (as illustrated in FIG. 6), so that when the leg 12 isre-assembled to the bed, the disc or layer 20 is secured against theunderside of the bed base 28.

Experiments have shown that the arrangement shown in FIG. 8 is onehundred percent effective in preventing bed bugs from traversing thedisc 20 and gaining access to a bed base 28. The experiments included atypical bed base platform 28 of pressed timber construction, to whichwere attached a first group of bed legs 12 in the normal manner (thecontrols), and a second group of bed legs provided with the discs asshown in FIG. 8. A heat source, similar in heat output to that of ahuman body, was placed on the platform.

Each of the groups of legs were variously provided with a source of bedbugs, including one source each of adult male and female bugs, and fiveof nymph bugs.

Table A of FIG. 9 shows the result of bed bug infestation in the absenceof protective barriers over a period of one week. It is clear thatvirtually all the bugs reached the bed base within the first two days ofthe experiment. In stark contrast, as shown in Table B, not one of thebugs was able to traverse the low friction material disc barrier 20. Asillustrated in FIG. 8, bed bugs in the second group ascended the bed leg12, but were unable to make the transition from the relatively roughvertical surface of the leg onto the low friction horizontal surface 26of the disc 20, which in the experiment were made of Teflon®.

It appears from the above described experiment that any extension of thebarrier, in the form of a disc, beyond the periphery of the bed leg,significantly wider than the length of the insects to be repelled, willprevent infestation. Preferably the projection of the disc beyond theperiphery of the leg should be at least three insect lengths and thuspreferably at least 15 mm for bed bugs.

Although the experiment was conducted with round bed legs andappropriately shaped disc barriers, it will be understood that theprinciples of the barrier may be equally well implemented with squaresof the barrier material as long as the projection of the material beyondthe leg periphery is sufficient.

Further Embodiments

The arrangements described above have relied on the property of lowcoefficient of friction to provide barrier to climbing insects, butother forms of barrier are envisaged by the present invention.

In one preferred arrangement the barrier may be formed by a surfacecoating which, although not necessarily having the property of lowcoefficient of friction, may be sufficiently unpleasant to the senses ofinsects as to dissuade them from traversing the barrier. Thus certainchemical compounds known to be inimical to insects or a particular groupof insects to be guarded against, can be applied in similar manner tothat described above; that is by a band of the compound applied around asupporting leg of a bed or the supporting substructure of an elevatedstructure. For example marine anti-fouling paint or like chemicalcomposition may be suitable for some groups of insects. The suitablechemical compound may be impregnated into a porous material formed intoa washer or gasket as described above and assembled to the upper portionof a bed leg. In this latter arrangement also, it is preferable if thewasher or gasket extends significantly beyond the periphery of the upperend of the leg.

The formation of an insect barrier which relies on properties whichpromote aversion in an insect, need not of course be restricted tovertical surfaces. Thus a perimeter band of a chemically formulatedmaterial may be applied to a horizontal surface, or placed across aknown route of insect infiltration.

Although the legs supporting a bed may be the most common route ofinfestation by bed bugs, it will be appreciated that alternative routesmay be available if the bed base or bedding is in contact with aseparate bed head or a wall. To cover this contingency, suitably′prepared offset blocks 30 may be provided between the bed head 32 and anadjacent wall 34 as shown in FIG. 10. These blocks are provided withsimilar bug impeding material, that is, for example by covering inTeflon® tape, or by impregnation or coating with a repellent chemicalcompound, such as for example, GoreTex and Kel-F, as described for thebed leg and bed support structures above.

Preferably, blocks for covering with Teflon® or other low coefficient offriction tape, are triangular in section and affixed to the bed head soas to present a sharp edge, for example the apex of an isoscelestriangle, uppermost and extending between the wall and the bed head.Thus only steeply sloping surfaces are presented between the wall andthe bed head. More preferably, the offsetting blocks 30 could beprovided with a ring or gasket 36 of low coefficient of frictionmaterial, with the ring or gasket 36 arranged to present a verticalsurface extending radially outwards from the block.

In another preferred arrangement shown in FIG. 11, offset blocks 40 maybe provided with a cup shaped barrier 42, formed of low coefficient offriction material, with outwardly extending rim 44, thus providingsurface interfaces shown to be proof against traversing by bed bugs. Inthis arrangement, the cup shaped barrier may be secured between theoffset block 40 and the surface of the bed head 32.

Offset blocks may be provided with a through aperture for accepting asecuring screw 46 as shown in FIG. 10.

In each of the embodiments described above, the layer or disc ofmaterial, the offset blocks and low coefficient of friction tape, mayconveniently be provided in packaged kit form suitable for retro-fittingto existing bed legs. Kits of discs with central apertures could be madeavailable in a selection of shapes and sizes to suit, for example,typical square and circular section bed legs. The number of discsprovided could vary for different bed configurations, for exampleranging from perhaps four for a small single bed, to nine for a largedouble bed.

With reference now to FIGS. 12 to 15, an insect infestation reductionsystem 100 is disclosed comprising a dual ring assembly of a firstouter-ring 102 and a second inner-ring 104, each outer and inner ringprovided with a central aperture. The first outer ring 102 may beconstructed of a semi-rigid plastic which is slippery and smooth, suchas for example Teflon as described above, to prevent a bed bug (or othercrawling insect) from traversing the first outer-ring. The secondinner-ring 104 may be constructed of a soft, highly flexible plasticmaterial or rubber to provide flexibility. The second inner-ring 104 mayfurther comprise an aperture 106 to conform and surround and affix to aleg 108 of an article of furniture such as a bed base 110, and hold thering assembly in place by friction, as shown in FIG. 15. Preferably, thesecond inner-ring 104 is constructed of a material with a sufficientsoftness and flexibility (e.g., Shore A 10-50, preferably near 20) toconform to the leg of an article of furniture without slipping, slidingor falling.

The second inner-ring may comprise a wide variety of shapes and/orsizes; the shape and/or size dependent upon the specific application.Such shapes and sizes may include (without limitation) round, square,triangular, hexagon, oval, or any other required shape. In a preferredembodiment, the inner diameter of the aperture 106 may be similar to thediameter of a common pencil. The aperture may have a larger diameter asneeded for the specific application.

The first outer-ring and the second outer-ring may be affixed to eachother by a variety of common methods. Such methods include the use ofadhesive or other common bonding agents (e.g., chemical bonding, heatbonding, welding, brazing, etc.). Bonding of the first outer-ring andthe second outer-ring may include casting on ring into/onto the otherduring manufacturing such that one ring is injected into the other.

Mechanical adhesion may also be used to affix the first outer-ring andthe second inner-ring, where the first outer-ring and/or the secondinner-ring include a mechanical feature. Mechanical adhesion may includeinstances where either the first outer-ring, the second inner-ring, orboth may include open areas, pits, divots, tabs, or other like features.Other mechanical features may include interlocking rings on each thefirst outer-ring and the second-inner ring. The exact specifications,materials used, and method of use of the insect infestation reductionsystem may vary upon manufacturing.

In one preferred arrangement as shown in FIG. 12, the soft elastomerinner ring 104 is assembled to the outer ring 102 by mechanical means,such as a ridge and undercut 112 locking the inner ring to the insiderim 114 of the aperture 116 of the outer ring.

In an alternative arrangement as shown in FIG. 13, the two rings 102 and104 are co-moulded in a two stage moulding operation within the onecavity of an injection moulding tool (not shown), In this arrangementthe inner ring is automatically bonded to the outer ring.

In yet a further arrangement as shown in FIG. 14, the outer ring 104 isprovided with a number of apertures 118 around the periphery of theaperture 116. The outer ring is moulded in a first operation and thenplaced in a second injection moulding cavity for the moulding of theinner ring. The soft elastomer of the inner ring fills the cavity butalso intrudes into the apertures of the outer ring, locking the tworings into an assembly.

1. A method of preventing infestation of a bed or other item offurniture by creeping insects; said method including the application ofa barrier at the legs of said bed or furniture; said barrier comprisingat least one disc or layer of material inimical to at least a selectionof said creeping insects; said disc or layer interposed between a groundsurface and the underside surface of a bed base of said bed or between aground surface and an upper structure of said furniture.
 2. The methodof claim 1 wherein at least one said disc or layer has a low coefficientof friction surface; said surface having properties preventing acreeping insect, traversing a substantially horizontal underside of saiddisc or layer.
 3. The method of claim 1 wherein said properties includea low coefficient of friction and resistance to van der Waal forces. 4.The method of claim 1 wherein said low coefficient of friction of saidsurface is a dynamic coefficient of friction less than 0.4.
 5. Themethod of claim 1 wherein said disc layer is composed ofpolytetrafluoroethylene or similar compounds; such compounds commonlyknown as Teflon®.
 6. The method of claim 1 wherein said disc or layer issized so as to extend beyond the periphery of said bed leg; an extendedportion of said disc or layer forming a substantially horizontal annularunderside surface beyond said periphery.
 7. The method of claim 1wherein said disc or layer is provided with a central aperture; saidaperture sized so as to allow passage therethrough of a securing bolt ofsaid bed leg.
 8. The method of claim 1 wherein said disc comprises adual ring assembly; the assembly including an outer ring and an innerring affixed to said outer ring; the outer ring formed of asubstantially rigid polymer with said low coefficient of friction; theinner ring formed of a flexible polymer; each said outer ring and saidinner ring provided with a central aperture.
 9. The method of claim 8wherein flexibility of said inner ring, provides for said dual ringassembly to be retained on a leg of a bed or other item of furniturepassing through said aperture in said inner ring; said dual ringassembly retained on said leg by friction between said leg and saidflexible inner ring.
 10. A method of reducing infestation of a bed byclimbing insects; said method including interposing insect impedingbarriers at supporting elements of said bed; said method including thesteps of: (a) detaching each supporting element of said bed; (b)applying said insect impeding barrier to an upper end of said supportingelement; (c) re-attaching said supporting elements to said bed such thatsaid barrier is interposed between said upper end of said supportingelement and an underside of said bed.
 11. The method of claim 10 whereinsaid supporting element is a bed leg; said bed leg attaching to anunderside of a bed base of said bed by a length of threaded rodprojecting from said upper end of said bed leg; said barrier formed as adisc or layer of low friction material; said disc or layer sized toproject radially from a periphery of said bed leg so as to expose anannular surface of said low friction material forming a substantiallyhorizontal underside surface between a periphery of said bed leg andsaid underside of said bed.
 12. The method of claim 10 wherein saidmethod includes the further steps of interposing offset blocks between abed head of said bed and an adjacent wall; said offset blocks includingan insect impeding barrier.
 13. The method of claim 12 wherein saidinsect impeding barrier includes application of a low coefficient offriction tape to surfaces of said offset blocks; said offset blocksconfigured so as to present one or more upwardly sloping upper surfaceonly, between said bed head and said adjacent wall.
 14. The method ofclaim 12 wherein said insect impeding barrier includes a ring of lowcoefficient of friction material; said ring of material includingvertical surfaces projecting radially from surfaces of said offsetblocks.
 15. A method of preventing infestation by creeping insects of abed or other elevated structure; the method operating according to themethod of claim 1; said method including the application of a barrier inthe form of a gasket or washer to the legs or substructure of said bedor other elevated structure; said barrier comprising a band of amaterial inimical to at least a selected group of said creeping insects.16. The method of claim 15 wherein said band of material is treated witha compound; said compound having properties repulsive to at least agroup of said creeping insects.
 17. The method of claim 16 wherein saidgasket or washer is formed of a porous material; said compoundimpregnated into said porous material.
 18. A disc of material forming abarrier extending generally radially from a periphery of a bed legbetween a floor surface and a bed base; said disc of material inimicalto traversing by bed bugs and other creeping insects; said disccomprising a dual ring assembly of an outer ring and an inner ringaffixed to said outer ring; said outer ring presenting an exposedsubstantially horizontal underside, annular portion, of low coefficientof friction material.
 19. The disc or layer of material of claim 18wherein said disc is provided with a central aperture for placement ofsaid discover a central securing bolt of a said bed leg or around saidbed leg.